In two pedigrees, three members possessed a mutation at position 816 of the amino acid sequence of KIT (D816G and D816V, Fig. 1; D816V, Fig. S1A), whereas the other MCAD-affected family members had varying mutations at other sites of KIT. There was no obvious relation between the KIT mutations and the clinical severity of MCAD. The gene discussed is KIT; the disease is medium chain acyl-CoA dehydrogenase deficiency.